Professor, School of Mechanical Engineering, Purdue University, West Lafayette, IN
Steven Johnson, W
Senior research scientist, NASA Langley Research Center, Hampton, VA
Several lay-ups of SCS-6/Ti-15-3 metal matrix composites were tested in either a center hole or a double-edge-notched geometry. At different cyclic stress levels, the number of cycles required to initiate a matrix fatigue crack at the notch was recorded. A strain-life fatigue curve was developed for the Ti-15-3 matrix material. A strain-life fatigue analysis method was developed that incorporates a modified Smith, Watson, and Topper effective strain parameter to account for local stress concentration at the notch tip and thermal residual stresses in the matrix material. This analysis method was used to predict the number of cycles required for matrix crack initiation at the notches. The predictions were in good agreement with the experimental data.
Paper ID: CTR10101J